2002 CHRYSLER CARAVAN overheating

CONDITION POSSIBLE CAUSES CORRECTION
INADEQUATE AIR
CONDITIONER
PERFORMANCE
(COOLING SYSTEM
SUSPECTED)1. Radiator and/or A/C condensor is
restricted, obstructed or dirty
(insects, leaves, etc.)1. Remove restriction or clean
debris from radiator or A/C
condensor.
2. Engine is overheating (heat may
be transferred from radiator to A/C
condensor. High underhood
temperatures due to engine
overheating may also transfer heat
to A/C condensor).2. Correct overheating
condition.
3. The cooling system is equipped
with air seals at the radiator and/or
A/C condensor. If these seals are
missing or damaged, not enough air
flow will be pulled through the
radiator and A/C condensor.3. Check for missing or
damaged air seals. Repair as
necessary.
INADEQUATE HEATER
PERFORMANCE. MAY BE
ACCOMPANIED BY LOW
GAUGE READING1. Diesel engines, due to their
inherent efficiency are slower to
warm up than gasoline powered
engines, and will operate at lower
temperatures when the vehicle is
unloaded.1. The lower gauge reading
may be normal.
2. Coolant level low. 2. Pressure test cooling system.
Repair leaks as necessary.
3. Obstruction in heater hose fitting
at engine.3. Remove heater hoses and
check for obstructions. Repair
as necessary.
4. Heater hose kinked. 4. Locate kinked area. Repair
as necessary.
5. Water pump is not pumping water
to heater core. When the engine is
fully warmed up, both heater hoses
should be hot to the touch. If only
one of the hoses is hot the water
pump may not be operating correctly.
The accessory drive belt may also
be slipping causing poor water pump
operation.5. Refer to water pumps in this
group. Repair as necessary. If a
slipping belt is detected, refer to
Engine Accessory Drive Belts in
this group. Repair as
necessary.
HEAT ODOR 1. Various heat shields are used at
certain drive line components. One
or more of these shields may be
missing.1. Locate missing shields.
Repair or replace as necessary.
2. Is temerature gauge reading
above the normal range?2. Refer to the previous
Temperature Gauge Reads
High in these Diagnostic
Charts. Repair as necessary.
3. Is the Cooling fan operating
correctly?3. Refer to Cooling System Fan
in this group for diagnosis.
Repair as necessary.
RGCOOLING 2.5L TURBO DIESEL7a-5
COOLING 2.5L TURBO DIESEL (Continued)
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RADIATOR PRESSURE CAP
DESCRIPTION
The cooling system pressure cap is located on the
radiator. The cap construction includes; stainless
steel swivel top, rubber seals, and retainer, main
spring, and a spring loaded valve (Fig. 19).
OPERATION
The cooling system is equipped with a pressure cap
that releases excessive pressure; maintaining a range
of 97-124 kPa (14-18 psi).
The cooling system will operate at higher than
atmospheric pressure. The higher pressure raises the
coolant boiling point thus, allowing increased radia-
tor cooling capacity.
There is also a vent valve in the center of the cap.
This valve also opens when coolant is cooling and
contracting, allowing the coolant to return to cooling
system from coolant reserve system tank by vacuum
through a connecting hose.If valve is stuck shut,
or the coolant recovery hose is pinched, the
radiator hoses will be collapsed on cool down.
Clean the vent valve (Fig. 19) and inspect cool-
ant recovery hose routing, to ensure proper
sealing when boiling point is reached.
The gasket in the cap seals the filler neck, so that
vacuum can be maintained, allowing coolant to be
drawn back into the radiator from the reserve tank.
If the gasket is dirty or damaged, a vacuum
may not be achieved, resulting is loss of coolant
and eventual overheating due to low coolant
level in radiator and engine.
DIAGNOSIS AND TESTING
DIAGNOSIS AND TESTING - COOLING SYSTEM
PRESSURE CAP
Dip the pressure cap in water. Clean any deposits
off the vent valve or its seat and apply cap to end of
the Pressure Cap Test Adaptor that is included with
the Cooling System Tester 7700. Working the
plunger, bring the pressure to 104 kPa (15 psi) on the
gauge. If the pressure cap fails to hold pressure of at
least 97 kPa (14 psi), replace the pressure cap.
CAUTION: The Cooling System Tester Tool is very
sensitive to small air leaks that will not cause cool-
ing system problems. A pressure cap that does not
have a history of coolant loss should not be
replaced just because it leaks slowly when tested
with this tool. Add water to the tool. Turn tool
upside down and recheck pressure cap to confirm
that cap is bad.
If the pressure cap tests properly while positioned
on Cooling System Tester (Fig. 20), but will not hold
pressure or vacuum when positioned on the filler
neck. Inspect the filler neck and cap top gasket for
irregularities that may prevent the cap from sealing
properly.
Fig. 19 Cooling System Pressure Cap Filler Neck
1 - OVERFLOW NIPPLE
2 - MAIN SPRING
3 - GASKET RETAINER
4 - STAINLESS-STEEL SWIVEL TOP
5 - RUBBER SEALS
6 - VENT VALVE
7 - PRESSURE BOTTLE
8 - FILLER NECK
Fig. 20 Testing Cooling System Pressure Cap
1 - PRESSURE CAP
2 - PRESSURE TESTER
RGENGINE7a-25
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(a) BCM has two battery feeds at pin 1 and pin
5 of the 6±way connector.
(b) Pin 5 of the (BX2) 32 way connector of the
BCM for ignition feed.
(c) Check voltage (PX2) connector, pin 34 for 12v.
(d) If voltage OK, go to step Step 3
(e) If NO voltage repair as necessary. Refer to
the appropriate wiring information. The wiring
information includes wiring diagrams, proper wire
and connector repair procedures, further details on
wire harness routing and retention, as well as pin-
out and location views for the various wire harness
connectors, splices and grounds.
(3) Check driver's seat belt buckle switch input
(form ORC) for a closed circuit when not buckled. If
input not seen, look for open in wiring or switch. The
switch is grounded when belt is not buckled.
(4) Verify PCI data bus communication between
ORC and BCM.
NO FASTEN SEAT BELT LAMP WHEN IGNITION
SWITCH IS TURNED ON.
(1) Check for burned out lamp.
(2) Using a voltmeter check for voltage at the clus-
ter conncctor:
(a) Pin 2 of the mechanical instrument cluster
for battery feed.
(b) Pin 11 of the mechanical instrument cluster
for ignition voltage.
(3) Repair as necessary.
FASTEN SEAT BELT LAMP OR TONE CONTINUES
FOR MORE THAN 10 SECONDS AFTER SEAT
BELTS ARE FASTENED AND DRIVER'S DOOR IS
CLOSED.
Refer to the proper Body Diagnostic Procedures
manual.
NO TONE WHEN PARK OR HEADLAMPS ARE ON
AND DRIVER'S DOOR IS OPEN.
Make sure ignition is in lock position with the key
removed.
(1) Check the BCM DTC's and BCM sensors to
verify the door is open. Repair as necessary.
(2) Actuate Chime (BCM actuates).
(3) Inspect BCM connectors and wires for proper
connection.
(4) Measure with a voltmeter the voltage (12v) on
BCM connector (PX2) pin 34 with harness connected.
DIAGNOSIS AND TESTING - DOME LAMP ON
CHIME
The dome lamp on chime will warn the driver that
the dome lamps have been left on.When the ignition is OFF and the key is out of the
ignition:
²Driver's door OPEN (door ajar switch is closed to
ground) and
²Dome lamps are ON (dome lamp switch is closed
to ground),
The chime will sound continuously until the driv-
ers door is closed, dome lamps turned OFF or until
the battery protection time out of 15 minutes has
expired. Chime rate: 168 to 192 chimes per minute.
DIAGNOSIS AND TESTING - ENGINE
TEMPERATURE CRITICAL CHIME
The engine temperature critical chime will warn
the driver that the vehicle's engine is overheating.
While monitoring the coolant temperature, the Pow-
ertrain Control Module (PCM) will send on the PCI
data bus as engine temperature every 1.376 seconds
to the cluster. The MIC calculates engine tempera-
ture and determines if a warning should occur. This
feature is functional only with the Ignition Switch in
the Run/Start position.
When the engine temperature reaches 122ÉC
(252ÉF) the MIC requests a chime from the BCM and
the engine temperature lamp comes ON. The MIC
turns OFF the lamp when the engine temperature
reaches 117ÉC (242ÉF). The MIC will chime continu-
ously (request from the BCM). The chime will turn
OFF after four minutes or when the temperature
reaches 117ÉC (242ÉF), which ever occurs first.
DIAGNOSIS AND TESTING - EXTERIOR LAMPS
ON CHIME
The exterior lamp on chime will warn the driver
that the exterior lights have been left on.
With the ignition switch OFF/key out of ignition:
²Driver's door is open (door ajar switch is closed
to ground)
²Parking lamps or headlamps ON (parking lamp
switch is closed to ground)
The chime will sound until lights are turned OFF,
driver's door closed or until the battery protection
time out of 3 minutes has expired.
Chime rate: 168 to 192 chimes per minute.
To test the exterior lamps left on function:
²Turn ignition off
²Remove ignition key
²Turn exterior lamps on with driver's door open.
Chime should sound until lamps are turned off or
driver's door is closed.
DIAGNOSIS AND TESTING - KEY-IN IGNITION
CHIME
The key-in ignition chime will act as a warning to
the driver that the ignition key has been left in the
8B - 2 CHIME/BUZZERRS
CHIME/BUZZER (Continued)
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Possible indications of the cylinder head gasket
leaking between adjacent cylinders are:
²Loss of engine power
²Engine misfiring
²Poor fuel economy
Possible indications of the cylinder head gasket
leaking between a cylinder and an adjacent water
jacket are:
²Engine overheating
²Loss of coolant
²Excessive steam (white smoke) emitting from
exhaust
²Coolant foaming
CYLINDER-TO-CYLINDER LEAKAGE TEST
To determine if an engine cylinder head gasket is
leaking between adjacent cylinders, follow the proce-
dures in Cylinder Compression Pressure Test (Refer
to 9 - ENGINE - DIAGNOSIS AND TESTING). An
engine cylinder head gasket leaking between adja-
cent cylinders will result in approximately a 50±70%
reduction in compression pressure.
CYLINDER-TO-WATER JACKET LEAKAGE TEST
WARNING: USE EXTREME CAUTION WHEN THE
ENGINE IS OPERATING WITH COOLANT PRES-
SURE CAP REMOVED.VISUAL TEST METHOD
With the engine cool, remove the coolant pressure
cap. Start the engine and allow it to warm up until
thermostat opens.
If a large combustion/compression pressure leak
exists, bubbles will be visible in the coolant.
COOLING SYSTEM TESTER METHOD
WARNING: WITH COOLING SYSTEM TESTER IN
PLACE, PRESSURE WILL BUILD UP FAST. EXCES-
SIVE PRESSURE BUILT UP, BY CONTINUOUS
ENGINE OPERATION, MUST BE RELEASED TO A
SAFE PRESSURE POINT. NEVER PERMIT PRES-
SURE TO EXCEED 138 kPa (20 psi).
Install Cooling System Tester 7700 or equivalent to
pressure cap neck. Start the engine and observe the
tester's pressure gauge. If gauge pulsates with every
power stroke of a cylinder a combustion pressure
leak is evident.
CHEMICAL TEST METHOD
Combustion leaks into the cooling system can also
be checked by using Bloc-Chek Kit C-3685-A or
equivalent. Perform test following the procedures
supplied with the tool kit.
REMOVAL - CYLINDER HEAD
(1) Perform fuel system pressure release procedure
before attempting any repairs.(Refer to 14 -
FUEL SYSTEM/FUEL DELIVERY - SPECIFICA-
TIONS)
(2) Disconnect battery negative cable.
(3) Drain cooling system. (Refer to 7 - COOLING -
STANDARD PROCEDURE)
(4) Remove air filter housing and inlet tube.
(5) Remove upper intake manifold. (Refer to 9 -
ENGINE/MANIFOLDS/INTAKE MANIFOLD -
REMOVAL)
(6) Remove heater tube support bracket from cyl-
inder head.
(7) Disconnect radiator upper and heater supply
hoses from intake manifold water outlet connections.
(8) Remove accessory drive belts. (Refer to 7 -
COOLING/ACCESSORY DRIVE/DRIVE BELTS -
REMOVAL)
(9) Raise vehicle and remove exhaust pipe from
manifold.
(10) Remove power steering pump reservoir and
line support bracket from lower intake manifold and
set aside. Do not disconnect lines.
(11) Remove ignition coil and wires from engine.
(12) Disconnect cam sensor and fuel injector wir-
ing connectors.
Fig. 13 Cylinder Head and Camshafts
1 - CAMSHAFT BEARING CAPS
2 - PLUG
3 - CAMSHAFT
4 - CYLINDER HEAD
5 - CAMSHAFT OIL SEAL
RSENGINE 2.4L9-25
CYLINDER HEAD (Continued)
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INSTALLATION
(1) Install air box into vehicle and onto the locat-
ing pin.
(2) Install bolt to hold air box to the upper radia-
tor cross member.
(3) Install the inlet hose to the throttle body.
(4) Connect the inlet air temperature sensor (Fig.
16).
(5) Connect the negative battery cable.
CYLINDER HEAD
DESCRIPTION
The aluminum cylinder heads (Fig. 17) are
designed to create high flow combustion chambers to
improve performance, while minimizing the change
to the burn rate in the chamber. The cylinder head
incorporates the combustion chamber. Two valves
per-cylinder are used with inserted valve seats and
guides. A multi-layer steel (MLS) type gasket is used
between the cylinder head and engine block.
OPERATION
The cylinder head closes the combustion chamber,
allowing the pistons to compress the fuel/air mixture
for ignition. The valves are actuated by the lobe pro-
files on the camshaft to open and close at specified
duration to either allow clean air in the combustion
chamber or the exhaust gases out; depending on the
stroke of the engine.
DIAGNOSIS AND TESTINGÐCYLINDER HEAD
GASKET
A cylinder head gasket leak can be located between
adjacent cylinders or between a cylinder and the
adjacent water jacket.
Possible indications of the cylinder head gasket
leaking between adjacent cylinders are:
²Loss of engine power
²Engine misfiring
²Poor fuel economy
Possible indications of the cylinder head gasket
leaking between a cylinder and an adjacent water
jacket are:
²Engine overheating
²Loss of coolant
²Excessive steam (white smoke) emitting from
exhaust
²Coolant foaming
CYLINDER-TO-CYLINDER LEAKAGE TEST
To determine if an engine cylinder head gasket is
leaking between adjacent cylinders, follow the proce-
dures in Cylinder Compression Pressure Test (Refer
to 9 - ENGINE - DIAGNOSIS AND TESTING). An
engine cylinder head gasket leaking between adja-
cent cylinders will result in approximately a 50±70%
reduction in compression pressure.
CYLINDER-TO-WATER JACKET LEAKAGE TEST
WARNING: USE EXTREME CAUTION WHEN THE
ENGINE IS OPERATING WITH COOLANT PRES-
SURE CAP REMOVED.
VISUAL TEST METHOD
With the engine cool, remove the coolant pressure
cap. Start the engine and allow it to warm up until
thermostat opens.
If a large combustion/compression pressure leak
exists, bubbles will be visible in the coolant.
COOLING SYSTEM TESTER METHOD
WARNING: WITH COOLING SYSTEM TESTER IN
PLACE, PRESSURE WILL BUILD UP FAST. EXCES-
SIVE PRESSURE BUILT UP, BY CONTINUOUS
ENGINE OPERATION, MUST BE RELEASED TO A
SAFE PRESSURE POINT. NEVER PERMIT PRES-
SURE TO EXCEED 138 kPa (20 psi).
Install Cooling System Tester 7700 or equivalent to
pressure cap neck. Start the engine and observe the
tester's pressure gauge. If gauge pulsates with every
power stroke of a cylinder a combustion pressure
leak is evident.
CHEMICAL TEST METHOD
Combustion leaks into the cooling system can also
be checked by using Bloc-Chek Kit C-3685-A or
equivalent. Perform test following the procedures
supplied with the tool kit.
REMOVAL - CYLINDER HEAD
(1) Drain the cooling system. (Refer to 7 - COOL-
ING - STANDARD PROCEDURE)
(2) Disconnect negative cable from battery.
(3) Remove upper and lower intake manifolds.
(Refer to 9 - ENGINE/MANIFOLDS/INTAKE MANI-
FOLD - REMOVAL)
WARNING: INTAKE MANIFOLD GASKET IS MADE
OF VERY THIN METAL AND MAY CAUSE PER-
SONAL INJURY, HANDLE WITH CARE.
9 - 100 ENGINE 3.3/3.8LRS
AIR CLEANER HOUSING (Continued)
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INSTALLATION
INSTALLATION - 2.4L ENGINE
(1) Remove any used O-rings from ends of power
steering hose.
(2) Using a lint free towel, wipe clean hose ends,
power steering pump fitting and steering gear port.
(3) Install new O-ring on power steering gear end
of return hose. Lubricate O-ring using clean power
steering fluid.
CAUTION: Use care not to bend tube ends of the
power steering hoses when installing. Leaks and
restrictions may occur.
CAUTION: If a new return hose is being installed
and it does not have an insulating heat sleeve
installed, the heat shield from the original hose
must be transferred before hose installation.
(4) Route hose along rear of cradle crossmember
and start gear end of hose into gear port. Do not
tighten hose tube nut at this time.
(5) Attach hose to suspension cradle crossmember
using two routing clamps and bolts (Fig. 19). Tighten
clamp bolts to 23 N´m (200 in. lbs.) torque.
(6) Tighten return hose tube nut at power steering
gear port to 31 N´m (275 in. lbs.) torque.
(7) Install the power steering fluid cooler on the
cradle crossmember reinforcement (Fig. 23). Install
the mounting bolts and tighten to 11 N´m (100 in.
lbs.).
CAUTION: Power steering fluid hoses must remain
away from the exhaust system and must not come
in contact with any unfriendly surfaces on the vehi-
cle.
(8) Route pump end of hose over cradle crossmem-
ber toward pump avoiding tight bends or kinking.
(9) Install return hose onto power steering pump
return fitting and secure with hose clamp (Fig. 19).
Tighten the screw-type clamp to a torque of 2 N´m
(18 in. lbs.).
CAUTION: To prevent overheating of power steering
fluid return hose, protective heat shield sleeve must
cover entire rubber hose.
(10) Slide insulating heat shield up over the clamp
on the return hose and tie-strap it in place.
(11) Install front emissions vapor canister. (Refer
to 25 - EMISSIONS CONTROL/EVAPORATIVE
EMISSIONS/VAPOR CANISTER - INSTALLATION)
(12) Lower vehicle.(13) Fill and bleed the power steering system
using the Power Steering Pump Initial Operation
Procedure. (Refer to 19 - STEERING/PUMP - STAN-
DARD PROCEDURE)
(14) Inspect system for leaks.
INSTALLATION - 3.3L/3.8L ENGINE
(1) Remove any used O-rings from ends of power
steering hose.
(2) Using a lint free towel, wipe clean hose ends
and power steering gear hose port.
(3) Install a new O-ring on gear port end of power
steering fluid hose. Lubricate O-ring using clean
power steering fluid.
CAUTION: Use care not to bend tube ends of the
power steering hoses when installing. Leaks and
restrictions may occur.
CAUTION: Power steering fluid hoses must remain
away from the exhaust system and must not come
in contact with any unfriendly surfaces on the vehi-
cle.
(4) Route hose (with cooler attached) up toward
reservoir avoiding tight bends or kinking.
(5) Start steering gear end of hose into gear port.
Do not tighten hose tube nut at this time.
(6) Attach return hose tubes to suspension cradle
crossmember using routing clamp and bolt (Fig. 20).
Tighten clamp bolt to 23 N´m (200 in. lbs.) torque.
(7) Install the power steering fluid cooler on the
cradle crossmember reinforcement (Fig. 23). Install
the mounting bolts and tighten to 11 N´m (100 in.
lbs.). When installing mounting bolts, include pres-
sure hose routing clamp.
(8) Tighten hose tube nut at power steering gear
port to 31 N´m (275 in. lbs.) torque.
(9) Install front emissions vapor canister. (Refer to
25 - EMISSIONS CONTROL/EVAPORATIVE EMIS-
SIONS/VAPOR CANISTER - INSTALLATION)
(10) Lower vehicle.
(11) Install return hose tube into retainer on ABS
bracket (Fig. 20). Close the bracket.
(12) Install return hose onto reservoir (Fig. 21).
Slide the hose clamp into position on fluid reservoir
and attach it.Be sure hose clamp in installed
past bead on fluid reservoir fitting.
(13) Fill and bleed power steering system using
the Power Steering Pump Initial Operation Proce-
dure. (Refer to 19 - STEERING/PUMP - STANDARD
PROCEDURE)
(14) Inspect system for leaks.
19 - 50 PUMPRS
HOSE - POWER STEERING RETURN (Continued)
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(6) Adjust transmission fluid level shown on the
indicator according to the chart.
(7) Check transmission for leaks.
Low fluid level can cause a variety of conditions
because it allows the pump to take in air along with
the fluid. As in any hydraulic system, air bubbles
make the fluid spongy, therefore, pressures will be
low and build up slowly.
Improper filling can also raise the fluid level too
high. When the transaxle has too much fluid, the
gears churn up foam and cause the same conditions
which occur with a low fluid level.
In either case, air bubbles can cause overheating
and/or fluid oxidation, and varnishing. This can
interfere with normal valve, clutch, and accumulator
operation. Foaming can also result in fluid escaping
from the transaxle vent where it may be mistaken
for a leak.
FLUID CONDITION
Along with fluid level, it is important to check the
condition of the fluid. When the fluid smells burned,
and is contaminated with metal or friction material
particles, a complete transaxle recondition is proba-
bly required. Be sure to examine the fluid on the dip-
stick closely. If there is any doubt about its condition,
drain out a sample for a double check.
MopartATF+4 (Automatic Transmission Fluid-
Type 9602) when new is red in color. The ATF is dyed
red so it can be identified from other fluids used in
the vehicle such as engine oil or antifreeze. The red
color is not permanent and is not an indicator of fluid
condition. As the vehicle is driven, the ATF will begin
to look darker in color and may eventually become
brown.This is normal.ATF+4 also has a unique
odor that may change with age. Consequently,odor
and color cannot be used to indicate the fluid
condition or the need for a fluid change.
After the fluid has been checked, seat the dipstick
fully to seal out water and dirt.
STANDARD PROCEDURE - FLUID AND FILTER
SERVICE
NOTE: Refer to the maintenance schedules in
LUBRICATION and MAINTENANCE, or the vehicle
owner's manual, for the recommended maintenance
(fluid/filter change) intervals for this transaxle.
NOTE: Only fluids of the type labeled MoparTATF+4
(Automatic Transmission Fluid) Type 9602 should
be used. A filter change should be made at the time
of the transmission oil change. The magnet (on the
inside of the oil pan) should also be cleaned with a
clean, dry cloth.NOTE: If the transaxle is disassembled for any rea-
son, the fluid and filter should be changed.
FLUID/FILTER SERVICE (RECOMMENDED)
(1) Raise vehicle on a hoist. Refer to LUBRICA-
TION and MAINTENANCE for proper procedures.
Place a drain container with a large opening, under
transaxle oil pan.
(2) Loosen pan bolts and tap the pan at one corner
to break it loose allowing fluid to drain, then remove
the oil pan.
(3) Install a new filter and o-ring on bottom of the
valve body (Fig. 212).
(4) Clean the oil pan and magnet. Reinstall pan
using new Mopar Silicone Adhesive sealant. Tighten
oil pan bolts to 19 N´m (165 in. lbs.).
(5) Pour four quarts of MopartATF+4 (Automatic
Transmission Fluid) Type 9602 through the dipstick
opening.
(6) Start engine and allow to idle for at least one
minute. Then, with parking and service brakes
applied, move selector lever momentarily to each
position, ending in the park or neutral position.
Fig. 212 Filter and O-Ring
1 - OIL FILTER
2 - O-RING
21 - 250 41TE AUTOMATIC TRANSAXLERS
FLUID (Continued)
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INSTALLATION
(1) Remove the tape or plugs from the evaporator
tube fittings and both expansion valve ports.
(2) Lubricate new rubber O-ring seals with clean
refrigerant oil and install them on the evaporator
tube fittings.
(3) Position the expansion valve onto the evapora-
tor tubes.
(4) Install and tighten the two screws that secure
the expansion valve to the evaporator tube sealing
plate. Tighten the screws to 11 N´m (97 in. lbs.).
(5) Reinstall the rear evaporator line extension
onto the expansion valve. (Refer to 24 - HEATING &
AIR CONDITIONING/PLUMBING - REAR/EVAPO-
RATOR - INSTALLATION - EVAPORATOR LINE
EXTENSION).
(6) Install the foam insulator wrap over the rear
expansion valve.
(7) Reinstall the rear heater-A/C unit housing into
the vehicle. (Refer to 24 - HEATING & AIR CONDI-
TIONING/DISTRIBUTION - REAR/REAR HEATER-
A/C HOUSING - INSTALLATION).
(8) Run the HVAC Cooldown Test to verify proper
operation.
HEATER CORE
DESCRIPTION
The rear heater core is located near the front of
the rear heater-A/C unit housing, behind the right
rear wheel house. It is a heat exchanger made of
rows of tubes and fins. One end of the core is fitted
with a molded plastic tank that includes integral
heater core inlet and outlet nipples. The heater core
can be serviced without removing the rear heater-A/C
unit housing from the vehicle. The heater core cannot
be repaired and, if faulty or damaged, it must be
replaced.
OPERATION
Engine coolant is circulated through heater hoses
to the heater core at all times. As the coolant flows
through the heater core, heat removed from the
engine is transferred to the heater core fins and
tubes. Air directed through the heater core picks up
the heat from the heater core fins. The blend air door
allows control of the heater output air temperature
by controlling how much of the air flowing through
the rear heater-A/C unit housing is directed through
the heater core.
STANDARD PROCEDURE - HEATER CORE
FILLING
In its final installed position, the rear heater core
is positioned higher than the radiator fill cap. There-fore, when the cooling system is drained and refilled,
gravity will not refill the heater core with coolant to
the proper level. This may result in two problems:1.
Insufficient coolant level in the engine cooling sys-
tem, which may result in engine overheating.2.Air
entrapped within the rear heater core, which may
result in insufficient rear heater performance. There
are two methods that may be employed to prevent
these problems:1.Pre-filling of the rear heater core.
2.Thermal cycling of the engine cooling system. Fol-
lowing are descriptions of both prevention methods,
as well as a method to verify rear heater perfor-
mance.
WARNING: REFER TO THE APPLICABLE WARN-
INGS AND CAUTIONS FOR THIS SYSTEM BEFORE
PERFORMING THE FOLLOWING OPERATION.
(Refer to 24 - HEATING & AIR CONDITIONING/
PLUMBING FRONT - WARNING - HEATER PLUMB-
ING).
PRE-FILLING
If the rear heater core or the rear heater-A/C hous-
ing have been removed from the vehicle for service,
the rear heater core may be pre-filled with the proper
engine coolant mixture prior to reconnecting the
heater hoses to the heater core hose fittings.
(1) The heater core should be installed in the rear
heater-A/C unit housing, and the rear heater-A/C
unit housing should be installed in the vehicle.
(2) Take the proper precautions to protect the car-
peting below the rear heater core from spilled engine
coolant and have absorbent toweling readily avail-
able to mop up any spills.
(3) Insert the small end of an appropriate funnel
into the upper hose fitting of the heater core (Fig. 4).
Fig. 4 Pre-Filling Heater Core - Typical
1 - REAR HEATER CORE
RSPLUMBING - REAR24 - 101
EXPANSION VALVE (Continued)
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